i say make this game in three parts
stewies part: trying to kill lois, there would be mini games platform levels, and puzzles that would be traps for lois to fall in, of course she doesn't die until a couple hours in
brians part: trying to bang lois, as any fan knows, brian really wants to do this. it would be the same thing mini games, platform levels, and puzzles, either trying to get lois drunk enough, or perhaps tricking her into thinking brian is mel gibson, george clooney, or some other "male hottie".
peters part: just do his life. dealing with stewie (have the option to help or stop him from killing lois) dealing with brian (same option as stewie) getting a job, the could do the fishing thing, jousting, working at pawtucket brewery, getting lois in the mood after trying to be killed by stewie and banged by brian. again mini games, platform levels, and puzzles.
i don't see any other way to make the game good, and funny.